128 Nemesis
Orbital characteristics 1
Orbit type Main belt (Nemesian)
Semimajor axis 2.750 AU
Perihelion distance 2.399 AU
Aphelion distance 3.101 AU
Orbital period 4.56 years
Inclination 6.25°
Eccentricity 0.128
Physical characteristics 1
Diameter 188.2 km
Rotation period 39 hours
Spectral class C
Abs. magnitude 7.49
Albedo 4 0.050
History 2
Discoverer J. C. Watson, 1872

128 Nemesis is a very large and very dark main belt asteroid, of carbonaceous composition. It rotates rather slowly, taking about one and half Earth days to complete one revolution.

Nemesis is the largest member of the Nemesian asteroid family bearing its name.

It was discovered by J. C. Watson on November 25, 1872 and named after Nemesis, the goddess of retribution in Greek mythology.

Nemesis is also the name of a hypothetical companion star of the sun.

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For other objects and regions, see: asteroid groups and families, binary asteroids, asteroid moons and the Solar system
For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names.